a. Field of the Invention.
This invention relates to processes and apparatus for controlling the winding of a filament onto a bobbin.
b. Prior Art.
It is known to sense the angle at which a filament is being wound onto the bobbin by using a movable element having an opening, such as a pigtail or eyelet, through which the filament passes. Lateral movement of the filament causes the element to move and the angle at which the filament is being wound onto the bobbin can be sensed, within limits, by the position of the element. Such a system has several disadvantages. One disadvantage is that, in almost every case, the eyelet or opening in the movable element is significantly larger than the filament, so that the winding angle of the filament can change to some extent without the element being moved to indicate such change. Also, the use of such a sensing element may tend to damage some filaments such as delicate optical fibers.
It is also known to pass a filament through a movable guide through which the filament is fed onto a bobbin and use a light source with two electroconductive cells positioned on opposite sides of the guide to sense the filament winding angle. One of the disadvantages of this system is that such a system cannot detect a small filament. Also, such a guide may tend to damage delicate filaments.